First off, welcome to the great hobby of RC flight.

Now, on to business. Everything that everyone here has said is true. Get a simulator (any is better than none, the physics and graphics will be better on the higher end simulators), a plane designed to be a trainer, and join the AMA and a club. Fly on the simulator as much as you possibly can, and get to where you can easily take off and land with a few different planes on the sim. Once you can do that, start your instruction at a club with a club instructor. You won't regret it. You'll not only learn the proper way to fly an airplane (IE, not learn the bad habbits that you may pick up learning on your own), as well as help from local pilots when you need it, and the comraderie of being with a group of people that enjoy doing the same thing you do.

Visit your local club before purchasing your first plane, as they can give you further recommendations on what to get and what they prefer to train on.

The Hangar 9 P-51 Mustang PTS is the trainer Mustang that was mentioned. I learned on one of them. It is a very good flying airplane, and does make a good trainer when used with the training gear. However, it's not the best trainer for everyone. If you get a good simulator, practice on the simulator frequently for a good while to get the basics and orientation to a somewhat familiar level, find an instructor that has either taught someone else on one or is open to the idea of teaching with one, and use the training gear, you will have a higher likelyhood of having success with the PTS Mustang. There is also another upside to going with the PTS Mustang (if it has been deemed the right trainer for you), and that is that it can also serve as your second plane by removing the training gear and installing the flap servos (if you go with the PTS Mustang, you will likely change the prop to a 2 bladed prop before you reach solo). It can also serve as somewhat of a 3rd plane by installing a more powerful engine in it, such as the OS .55AX, Saito 72, or Saito 82, giving it more performance and giving you more of a feel of what's to come from more advanced airplanes. It is a glow powered plane, but should be able to be converted to electric with a few part changes. If you do choose to go the electric conversion route, I'd recommend getting the Hangar 9 P-51 Mustang 40 ARF. It's essentially the same airplane as the PTS Mustang Mk. II, but you'll have to choose your power source, radio gear, servos, and buy the wing droops and speed brakes serperately. It is fitted for retracts, but includes fixed gear (if I'm not mistaken), which you should use at least until you're comfortable flying the plane in it's "high performance" configuration (no training aids).